At-home monitoring of cardiac activity and metrics of cardiac activity is an area of intense interest, because it offers the potential for vastly improving patient quality of life and life expectancy, as well as substantially reducing health care costs. For example congestive heart failure (CHF) is a common, costly, disabling, and potentially deadly condition. In developed countries, around 2% of adults suffer from heart failure, but in those over the age of 65, this increases to 6-10%. Although warning factors for CHF episodes (symptoms), including changes in cardiac rhythm, heart rate, and heart rate variability, have been identified, monitoring of patient's outside of the hospital setting has proven difficult and expensive. Thus, there is a well-established need for such (e.g., “at home”) monitoring.
Congestive heart failure, myocardial infarction, and other cardiac problems are fatal to a large number of people every year. Congestive heart failure and other cardiac problems can happen suddenly and be fatal without immediate treatment. Patients with cardiac problems can feel fine after being treated by a doctor to evaluate the patient's medication intake and cardiac functions. However, cardiac problems can arise between appointments and possibly lead to fatal cardiac events.
Changes in federal regulations of Medicare can penalize hospitals for emergency room admission of patients recently treated for cardiac problems. The new penalties provide additional incentives for the hospitals and doctors to monitor the cardiac health of the patient to ensure good cardiac health between appointments or to catch possible problems before a cardiac event requiring a visit to the emergency room occurs. Therefore, improved monitoring of the cardiac health of the patient is desired. Early diagnosis of a potential symptom or problem can result in treatment that prevents a fatal cardiac event.
Described herein are methods, devices, and systems for monitoring cardiac performance that may address this need. In particular, described herein are methods and systems (including software/firmware) for using or adapting for use one or more widely available communications or telecommunications devices, such as smart phones, tablet computers, or portable computers, to monitor one or more cardiac performance indicators, including a seismocardiogram (SCG). These methods and system may record, analyze, receive, and/or send cardiac performance information (including but not limited to digital health information) and/or indicators of cardiac performance (e.g., “indexes”) that may be understood by medical professionals. The devices, systems and methods may also provide direct patient feedback, both in assisting the patient to take (by themselves) a correct and/or accurate reading, and for providing an indicator of general health, including triggering an alarm. For example, a patient may record and provide access to detected health information (e.g., blood pressure, ECG, SCG, blood sugar, temperature, telemetry, etc.) to medical professionals using the methods and devices described herein. Access may be provided by uploading the medical information to a server and/or website; the website may be used to store, provide remote access to the user and/or qualified medical professionals, or analyze the health information.
Although this application focuses primarily on the use of seismocardiography using a personal communications device (e.g., smart phone), many of the principles described herein may be applied to other cardiac metrics and indices. Further, some of the principles described herein may be applied to methods and systems that may be used without a personal communications device.
Although the prior art has acknowledged the need for personal (e.g., at-home) monitoring devices, including those capable of performing and/or analyzing seismocardiography, no effective, lightweight, portable and patient-ready monitoring device has yet been developed or made available. For example, “Mechanisms Underlying Isovolumic Contraction and Ejection Peaks in Seismocardiogram Morphology” by Gurev et al. (Journal of Medical and Biological Engineering, 32(2): 103-110 (2012)) disclose a prior art setup for simultaneously taking a SCG and ECG. The equipment used in Gurev (see FIG. 1) is large, expensive, and impractical for home use. In contrast, the devices and methods disclosed herein enable the user to take an ECG and SCG at home using a hand held device, such as a mobile telecommunications device, as shown in FIG. 2.
“Seismocardiography—a non-invasive method of assessing systolic and diastolic left ventricular function in ischaemic heart disease” by Korzeniowska-Kubacka et al. (Folia Cardiol. 2006, Vol. 13, No. 4, pages 319-325) discloses using a seismocardiograph to measure cardiac function during exercise. The methods and apparatuses are administered by a medical professional in a medical office and require larger equipment that is not practical for home use or for a patient to self administer.
“A continuous, wearable, and wireless heart monitor using head ballistocardiogram (BCG) and head electrocardiogram (ECG).” By He et al. (Conf. Proc. IEEE Eng. Med. Biol. Soc. 2011, pages 4729-32) discloses a wearable heart monitoring sensor that has the form factor of a hearing aid that can communicate wirelessly with a computer device. However, the system requires the use of a separate piece, such as the in ear sensor, along with a computing device. The use of multiple pieces makes it more difficult for elderly patients to use the setup and decreases the likelihood that the patient will use the device.
U.S. Patent Application Publication No. 2009/0024045 discloses using an implanted medical device to directly measure various cardiac functions. The measurements require that the medical device is implanted within the patient's body. The methods, systems, and devices disclosed herein offer significant advantages because they do not require an invasive implanted medical device and can be used to quickly and conveniently measure a number of cardiac parameters with the patient in the comfort of their home.
U.S. Pat. No. 6,024,705 discloses using a seismic sensor to take an SCG along with a computer to analyze the waveform and output a numerical value representing cardiac performance. These devices are also impractical for home use or self-testing. The methods and devices are not used (or compatible with use) with a mobile telecommunications device.
U.S. patent application Ser. No. 12/796,188, filed Jun. 8, 2010 and titled “HEART MONITORING SYSTEM USABLE WITH A SMART PHONE OR COMPUTER,” now U.S. Pat. No. 8,509,882 and U.S. patent application Ser. No. 13/108,738, filed May 16, 2011 and titled “WIRELESS, ULTRASONIC PERSONAL HEALTH MONITORING SYSTEM,” now Publication No. US-2011-0301439-A1, describe ECG monitors that convert ECG data into ultrasound signals that can be received by a telecommunications device such as a smartphone and then stored, analyzed, and/or displayed. The instant application extends and adapts this teaching and may be used with any of the systems, methods, and devices described herein.